1991 Volume 8 Issue 1 Pages 35-42
Foaming of lubricating oil in a rotary compressor induces flowing out of the oil from the compressor, which deteriorates reliability of the compressor. This study investigates foaming characteristics of oil-refrigerant mixture by using an experimental apparatus which models foaming in the compressor. The experiments reveal that the foaming caused by blade rotation can be controlled by a plate which prevents a vortex from swallowing up the vapor and that the foaming caused by vapor blow can be depressed by a blow pipe extending above the mixture. Based on these results, measures to control foaming in a practical rotary compressor are investigated by using an experimental refrigerating cycle. From measurement of the foaming, it is proved that a simple cover which separates discharge blow from the mixture under a motor has a great effect of defoaming. Collection of oil which is pumped up through a shaft is also effective in decreasing the foaming. In addition, improvement of transient performance of the cycle is obtained by controlling the foaming.
